This proposal is a competitive renewal application for our research program on the role of the Caspase family of proteases, the c-Jun NH2-terminal kinase (JNK), and the phosphatidylserine receptor (PSR) in neuronal apoptosis in brain development and neurological diseases. In the present project, we will extend our research of these signaling pathways with a new emphasis on the mechanism of apoptosis and renewal of neural progenitor cells. Aim 1: We will investigate the mechanism downstream of phosphatidylserine and phosphatidylserine receptor (PS-PSR) recognition leading to the apoptosis of neural progenitor cells. We will express PS on the outer cell surface of neural progenitor cells and examine the signaling events following PS-PSR recognition. In addition, we will test whether the disruption of PS-PSR recognition in the embryonic brain will alter the apoptosis of neural progenitor cells. Aim 2: We will examine the interaction between the JNK and canonical Wnt/beta-catenin signaling in the decision of self-renewal or cell-cycle exit by neural progenitor cells. We will determine whether the canonical Wnt/beta-catenin pathway mediates self-renewal, and whether JNK activation attenuates the canonical Wnt/ beta-catenin signaling to promote differentiation of the daughter cells. Aim 3: We will use a transgenic system to calculate the net increase of adult-generated neurons in the mouse brain. In addition, we will test whether EGF and FGF2 infusion can accelerate adult neurogenesis and attract newly born neurons into stroke damaged brain areas. In summary, the present project is built on our research of JNK, phosphatidylserine receptor (PSR), and canonical Wnt/beta-catenin signaling with an emphasis on the mechanism governing the adjustment of the number of neural progenitor cells (Aim 1), the decision of cell-cycle exit by neural progenitor cells (Aim 2), and the accelerated neurogenesis after brain injury (Aim 3). These studies will enhance our understanding of neural plasticity and functional recovery after brain injury. [unreadable] [unreadable]